The present invention relates to filtration systems for removing contaminants from industrial fluids and the like, and in particular to a liquid coalescer media and method.
Filtration systems for industrial fluids are generally well known in the art. For example, contaminants, including solid particles and dispersed contaminant liquid water particles, must be removed from oil based industrial liquids, such as petrochemicals in the nature of gasoline, diesel fuel, jet fuel, gear oil, hydraulic fluid, lubricating oils, etc., organic and/or vegetable oils, bio-fuels, petrodiesel-biodiesel fuel blends, etc., as well as synthetic based lubricants and the like, to ensure proper long term operation and protection of the associated equipment. In the case of internal combustion engines, turbines, turbine driven equipment and other similar machines, to achieve long term predicable and profitable performance, both the fuel and the lubrication must be free from water contaminant and also free from solid particles. In the case of lubricants, oil conditioning systems are used in preventing lubricant oxidation and viscosity breakdown which set the stage for equipment failure due primarily to metal to metal contact between moving parts of the machinery. Preferably, filtration and related conditioning systems quickly and efficiently remove harmful water, particulate and other contaminants from fuels, lubrication oils, and other similar industrial fluids.
The separation of liquid water droplet dispersions from oil based industrial fluids is becoming increasingly important in today's technology, whether it is achieved by chemical extraction processing, effluent treatment, purification of fuels and lubricants, or emerging bio-fuel processing. The need to remove free water from such liquids is particularly stringent with liquid hydrocarbon fuel and biodiesel, which are often combined with rich additives, since even a small water content in these fuels results in corrosion of engine components and promotes microbiological growth in the fuel tank. Biodiesel fuels in particular tend to collect water quickly, especially in warmer environments. Surfactants are often added to such fuels to disperse any emulsified water therein into fine particles in an effort to promote proper engine performance. However, such surfactants make it very difficult to separate the water from the fuel. The presence of water alters the ability of the fuel to be effectively filtered, due to its physical property changes, and also accelerates fatigue wear in highly stressed mechanical components. All these factors clearly adversely impact the durability and performance of the engine system. In general, contaminated fuels harm equipment and interrupt or slow down process operations which results in expensive downtime, reduced efficiency and increased costs. For these reasons, current trade standards limit the maximum water content in both petrodiesel and biodiesel fuels to 500.0 ppm, while European Union diesel specifications further reduce the maximum water content in petrodiesel fuel and some biodiesel blends to 200.0 ppm.
The presence of a large water content in fuels treated with surfactants and/or additives disarms conventional coalescer elements in two ways:
1. Surfactants reduce the interfacial tension between wetted fibrous coalescer media surfaces and attached water droplets, resulting in detachment problems of water droplets on the fibrous coalescence media, and reduced coalescence effectiveness; and
2. Large water content in these fuels results in clogging the fibrous coalescer element, which ruins both coalescer effectiveness and efficiency.
Some prior filtration systems for lubricating oils, such as that disclosed in U.S. Pat. No. 6,422,396, use a multistep filtration process, wherein a separate particle filter element is positioned upstream of a standalone coalescer element to filter solid particles out of the lubricating oil before the dispersed water contaminant is removed from the partially filtered oil. While such devices are generally effective for lubricating oils, they are not suitable for use with fuels, and have a rather complicated construction, provide significant resistance to fuel flow through the system, and do not always remove enough free and emulsified water from the liquid to meet the ever increasing specifications required by modern industrial equipment.
Hence, a coalescer element having an uncomplicated construction, with reduced resistance to fluid flow and increased effectiveness and efficiency in removing in a single pass even large quantities of dispersed contaminant liquid water particles from oil based industrial liquids, including those treated with surfactants or the like, would clearly be beneficial.